The role of marine fish-produced carbonates in the oceanic carbon cycle is determined by size, specific gravity, and dissolution rate.

Rising CO2 emissions have heightened the necessity for increased understanding of Earth's carbon cycle to predict future climates. The involvement of marine planktonic species in the global carbon cycle has been extensively studied, but contributions by marine fish remain poorly characterized. Marine teleost fishes produce carbonate minerals ('ichthyocarbonates') within the lumen of their intestines which are excreted at significant rates on a global scale. However, we have limited understanding of the fate of excreted ichthyocarbonate. We analyzed ichthyocarbonate produced by three different marine teleosts for mol%MgCO3 content, size, specific gravity, and dissolution rate to gain a better understanding of ichthyocarbonate fate. Based on the species examined here, we report that 75 % of ichthyocarbonates are ≤0.91 mm in diameter. Analyses indicate high Mg2+ content across species (22.3 to 32.3 % mol%MgCO3), consistent with previous findings. Furthermore, ichthyocarbonate specific gravity ranged from 1.23 to 1.33 g/cm3, and ichthyocarbonate dissolution rates varied among species as a function of aragonite saturation state. Ichthyocarbonate sinking rates and dissolution depth were estimated for the Atlantic, Pacific, and Indian ocean basins for the three species examined. In the North Atlantic, for example, ~33 % of examined ichthyocarbonates are expected to reach depths exceeding 200 m prior to complete dissolution. The remaining ~66 % of ichthyocarbonate is estimated to dissolve and contribute to shallow water alkalinity budgets. Considering fish biomass and ichthyocarbonate production rates, our results support that marine fishes are critical to the global carbon cycle, contributing to oceanic alkalinity budgets and thereby influencing the ability of the oceans to neutralize atmospheric CO2.

Physiological trade-offs, acid-base balance and ion-osmoregulatory plasticity in European sea bass (Dicentrarchus labrax) juveniles under complex scenarios of salinity variation, ocean acidification and high ammonia challenge.

In this era of global climate change, ocean acidification is becoming a serious threat to the marine ecosystem. Despite this, it remains almost unknown how fish will respond to the co-occurrence of ocean acidification with other conventional environmental perturbations typically salinity fluctuation and high ammonia threat. Therefore, the present work evaluated the interactive effects of elevated pCO2, salinity reduction and high environmental ammonia (HEA) on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to seawater (32 ppt), to brackish water (10 ppt) and to hyposaline water (2.5 ppt). Following acclimation to different salinities for at least two weeks, fish were exposed to CO2-induced water acidification representing present-day (control pCO2, 400 µatm, LoCO2) and future (high pCO2, 1000 µatm, HiCO2) sea-surface CO2 level for 3, 7 and 21 days. At the end of each exposure period, fish were challenged with HEA for 6 h (1.18 mM representing 50% of 96 h LC50). Results show that, in response to the individual HiCO2 exposure, fish within each salinity compensated for blood acidosis. Fish subjected to HiCO2 were able to maintain ammonia excretion rate (Jamm) within control levels, suggesting that HiCO2 exposure alone had no impact on Jamm at any of the salinities. For 32 and 10 ppt fish, up-regulated expression of Na+/K+-ATPase was evident in all exposure groups (HEA, HiCO2 and HEA/HiCO2 co-exposed), whereas Na+/K+/2Cl- co-transporter was up-regulated mainly in HiCO2 group. Plasma glucose and lactate content were augmented in all exposure conditions for all salinity regimes. During HEA and HEA/HiCO2, Jamm was inhibited at different time points for all salinities, which resulted in a significant build-up of ammonia in plasma and muscle. Branchial expressions of Rhesus glycoproteins (Rhcg isoforms and Rhbg) were upregulated in response to HiCO2 as well as HEA at 10 ppt, with a more moderate response in 32 ppt groups. Overall, our findings denote that the adverse effect of single exposures of ocean acidification or HEA is exacerbated when present together, and suggests that fish are more vulnerable to these environmental threats at low salinities.

The role of maternal age and context-dependent maternal effects in the offspring provisioning of a long-lived marine teleost.

Despite evidence of maternal age effects in a number of teleost species, there have been challenges to the assertion that maternal age intrinsically influences offspring quality. From an evolutionary perspective, maternal age effects result in young females paradoxically investing in less fit offspring despite a greater potential fitness benefit that might be gained by allocating this energy to individual somatic growth. Although a narrow range of conditions could lead to a maternal fitness benefit via the production of lower quality offspring, evolutionary theorists suggest these conditions are seldom met and that the reported maternal age effects are more likely products of the environmental context. Our goal was to determine if maternal effects operated on offspring provisioning in a long-lived rockfish (genus Sebastes), and to evaluate any such effects as an intrinsic function of maternal age or a context-dependent effect of the offspring release environment. We found that offspring provisioning is a function of both maternal age and the timing of offspring release; older females exhibit increased provisioning over younger females throughout the spawning season despite a decrease in provisioning across all maternal ages as the season progresses. These findings suggest a role for both maternal age effects and a potential context-dependent maternal effect in population productivity, carrying important implications when modelling population persistence and resilience.

Comparative cytogenetic analysis of marine needlefishes (Beloniformes) from southern Brazil.

Cytogenetic studies have assisted in the taxonomic classification of organisms, especially those involving species with highly similar morphologic characteristics, or so-called cryptic species. Strongylura marina and Strongylura timucu collected from Paranaguá Bay, Paraná Coast in Southern Brazil are considered cryptic species, and the identification of interspecific variations based on the number and/or morphology of its chromosomes may serve as differentiating cytotaxonomic markers. Chromosomes of the two species were subjected to different banding and staining methods (C-, Ag-, and DAPI-CMA3), as well as chromosomal mapping of major rDNA (45S), revealed with an 18S probe by fluorescence in situ hybridization (FISH). The pattern of distribution of constitutive heterochromatin showed distinct features involving the pericentromeric and telomeric bands in both species. In S. marina, chromosome 1 represents the main species-specific marker, appearing almost entirely heterochromatic. In both species, the 45S rDNA is located at terminal region of the short arm of the chromosome 6, as detected by silver nitrate staining and FISH. Despite the apparent conserved diploid number of 48 chromosomes, data on the karyotype microstructure characterize the cytogenetic profile of the genus and may allow the establishment of cytotaxonomic and evolutionary inferences for these fishes.

Interactive effect of high environmental ammonia and nutritional status on ecophysiological performance of European sea bass (Dicentrarchus labrax) acclimated to reduced seawater salinities.

We investigated the interactive effect of ammonia toxicity, salinity challenge and nutritional status on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to normal seawater (32ppt), to brackish water (20ppt and 10ppt) and to hyposaline water (2.5ppt). Following acclimation to different salinities for two weeks, fish were exposed to high environmental ammonia (HEA, 20mg/L ∼1.18mM representing 50% of 96h LC50 value for ammonia) for 12h, 48h, 84h and 180h, and were either fed (2% body weight) or fasted (unfed for 7 days prior to HEA exposure). Biochemical responses such as ammonia (Jamm) and urea excretion rate, plasma ammonia, urea and lactate, plasma ions (Na(+), Cl(-) and K(+)) and osmolality, muscle water content (MWC) and liver and muscle energy budget (glycogen, lipid and protein), as well as branchial Na(+)/K(+)-ATPase (NKA) and H(+)-ATPase activity, and branchial mRNA expression of NKA and Na(+)/K(+)/2Cl(-) co-transporter (NKCC1) were investigated in order to understand metabolic and ion- osmoregulatory consequences of the experimental conditions. During HEA, Jamm was inhibited in fasted fish at 10ppt, while fed fish were still able to excrete efficiently. At 2.5ppt, both feeding groups subjected to HEA experienced severe reductions and eventually a reversion in Jamm. Overall, the build-up of plasma ammonia in HEA exposed fed fish was much lower than fasted ones. Unlike fasted fish, fed fish acclimated to lower salinities (10ppt-2.5ppt) could maintain plasma osmolality, [Na(+)], [Cl(-)] and MWC during HEA exposure. Thus fed fish were able to sustain ion-osmotic homeostasis which was associated with a more pronounced up-regulation in NKA expression and activity. At 2.5ppt both feeding groups activated H(+)-ATPase. The expression of NKCC1 was down-regulated at lower salinities in both fed and fasted fish, but was upregulated within each salinity after a few days of HEA exposure. Though an increment in plasma lactate content and a decline in energy stores were noted for both feeding regimes, the effect was more severe in feed deprived fish. Overall, several different physiological processes were disturbed in fasted sea bass during HEA exposure while feeding alleviated adverse effects of high ammonia and salinity challenge. This suggests that low food availability can render fish more vulnerable to external ammonia, especially at reduced seawater salinities.

Glicosaminoglicanos isolados da pele de palombeta (Chloroscombrus chrysurus) e guaiúba (Ocyurus chrysurus): características e implicações biológicas / Glycosaminoglycans isolated from the skin of 'palombeta' (Chloroscombrus chrysurus) and 'guaiúba' (Ocyurus chrysurus): features and biological implications

O Brasil abriga uma das maiores biodiversidades marinhas do mundo, favorecendo a descoberta de fontes alternativas de compostos farmacológicos. Desta forma, objetivou-se avaliar o potencial anticoagulante de glicosaminoglicanos (GAGs) isolados das peles da palombeta (Chloroscombrus chrysurus) e guaiúba (Ocyurus chrysurus). Os GAGs foram extraídos com papaína bruta em tampão acetato de sódio 0,1 M (pH 5,0) contendo cisteína 5 mM e EDTA 5 mM, seguido por cromatografia de troca iônica do extrato total em coluna de DEAE-celulose. As frações obtidas foram analisadas quanto à composição química (proteínas contaminantes e carboidratos totais) e os GAGs identificados por eletroforese em gel de agarose a 0,5%. Os ensaios de atividade anticoagulante foram realizados por meio do tempo de tromboplastina parcial ativada (TTPA) usando plasma humano normal e heparina-padrão (193,00 UI mg-1). O procedimento de obtenção e fracionamento dos GAGs mostrou-se eficiente, indicando semelhantes perfis cromatográficos entre as espécies avaliadas e, revelando para C. chrysurus, bandas com mobilidades semelhantes ao dermatam sulfato e com atividade de apenas 3,30 UI mg-1.

A great number of pharmacological compounds is found in the Brazilian marine diversity. This study evaluated the anticoagulant potential of glycosaminoglycans (GAGs) isolated from the skin of 'palombeta' Chloroscombrus chrysurus and 'guaiúba' Ocyurus chrysurus. GAGs were extracted with crude papain in 0.1 M sodium acetate buffer (pH 5.0) containing 5 mM cysteine and 5 mM EDTA, followed by ion exchange chromatography on DEAE-cellulose column. The chemical composition (contaminant proteins and total carbohydrates) and the analysis by 0.5% agarose gel electrophoresis of fractions were also determined. Anticoagulant assays were performed by activated partial thromboplastin time (APTT) using normal human plasma and standard heparin (193.00 IU mg-1). The obtaining and fractionation procedures of GAGs were effective and similar chromatographic profiles were verified between the species. A similar mobility to dermatan sulfate was revealed for C. chrysurus. This GAG also showed a low activity of 3.30 IU mg-1.

Glycosaminoglycans isolated from the skin of palombeta (Chloroscombrus chrysurus) and guaiúba (Ocyurus chrysurus): features and biological implications - doi: 10.4025/actascibiolsci.v34i2.6056 / Glicosaminoglicanos isolados da pele de palombeta (Chloroscombrus chrysurus) e guaiúba (Ocyurus chrysurus): características e implicações biológicas - doi: 10.4025/actascibiolsci.v34i2.6056

A great number of pharmacological compounds is found in the Brazilian marine diversity. This study evaluated the anticoagulant potential of glycosaminoglycans (GAGs) isolated from the skin of palombeta Chloroscombrus chrysurus and guaiúba Ocyurus chrysurus. GAGs were extracted with crude papain in 0.1 M sodium acetate buffer (pH 5.0) containing 5 mM cysteine and 5 mM EDTA, followed by ion exchange chromatography on DEAE-cellulose column. The chemical composition (contaminant proteins and total carbohydrates) and the analysis by 0.5% agarose gel electrophoresis of fractions were also determined. Anticoagulant assays were performed by activated partial thromboplastin time (APTT) using normal human plasma and standard heparin (193.00 IU mg-1). The obtaining and fractionation procedures of GAGs were effective and similar chromatographic profiles were verified between the species. A similar mobility to dermatan sulfate was revealed for C. chrysurus. This GAG also showed a low activity of 3.30 IU mg-1.

O Brasil abriga uma das maiores biodiversidades marinhas do mundo, favorecendo a descoberta de fontes alternativas de compostos farmacológicos. Desta forma, objetivou-se avaliar o potencial anticoagulante de glicosaminoglicanos (GAGs) isolados das peles da palombeta (Chloroscombrus chrysurus) e guaiúba (Ocyurus chrysurus). Os GAGs foram extraídos com papaína bruta em tampão acetato de sódio 0,1 M (pH 5,0) contendo cisteína 5 mM e EDTA 5 mM, seguido por cromatografia de troca iônica do extrato total em coluna de DEAE-celulose. As frações obtidas foram analisadas quanto à composição química (proteínas contaminantes e carboidratos totais) e os GAGs identificados por eletroforese em gel de agarose a 0,5%. Os ensaios de atividade anticoagulante foram realizados por meio do tempo de tromboplastina parcial ativada (TTPA) usando plasma humano normal e heparina-padrão (193,00 UI mg-1). O procedimento de obtenção e fracionamento dos GAGs mostrou-se eficiente, indicando semelhantes perfis cromatográficos entre as espécies avaliadas e, revelando para C. chrysurus, bandas com mobilidades semelhantes ao dermatam sulfato e com atividade de apenas 3,30 UI mg-1.